The present invention relates to a piezoelectric device for use in filter, oscillators, and other electric circuits. More particularly, the present invention relates to an improvement in the assembly of the piezoelectric device.
Recently, in the field of electronics, many developments have been made to a technology of packaging integrated-circuit chips. However, there have been made little development on the technology of packaging piezoelectric elements alone or together with integrated-circuit chips.
From the viewpoint of external appearance, the package having a plurality of externally extending terminals aligned in one row along a side of the package is called a single-in-line package while the package having two rows of terminals one on each of opposite sides of the package is called a dual-in-line package. In general, all the packages having at least one row of terminals are called an in-line package.
Since a piezoelectric element produces mechanical vibration during operation, it has been a difficult task to rigidly support the piezoelectric element in the package without deteriorating its vibrating action.
Furthermore, since the piezoelectric element is considerably large in size compared with the integrated-circuit, it has also been a difficult task to render an electric connection between electrodes applied on the piezoelectric element and aligned terminals within the small size packages, particularly, when one or more piezoelectric elements are to be incorporated in one package.
It is a primary object of the present invention to provide a piezoelectric device which is compact in size, simple in construction and can readily be manufactured at low cost.
It is another object of the present invention to provide a piezolectric device of the above described type including a piezoelectric unit which suppresses the spurious mode.
It is a further object of the present invention to provide a piezoelectric device of the above described type which can easily support the piezoelectric unit without deteriorating its vibrating action.
It is a still further object of the present invention to provide a piezoelectric device of the above described type which operates in a stable condition regardless of the supporting pressure applied to the piezoelectric unit.
In accordance with a preferred embodiment of the invention, a piezoelectric device comprises a casing and at least one piezoelectric unit incorporated in the casing. The piezoelectric unit according to the present invention comprises a piezoelectric body having first and second flat surfaces disposed in parallel to each other. On the piezoelectric body, a first group of electrodes are laminated on the first surface except one peripheral portion, a second group of electrodes are laminated on the second surface, and an extended electrode are laminated on the one peripheral portion of the first surface in a separate relation to the first group of electrodes. A runner electrode is provided for connecting the second group of electrodes with the extended electrode. The piezoelectric device further comprises first and second attaching means rigidly held in the casing and attached to the first and second surfaces of the piezoelectric unit, respectively, for vibrantly supporting the piezoelectric unit. The electrodes of the first and second groups on the piezoelectric body are connected to first and second groups of terminal members, respectively. Each of the terminal members has a terminal leg extending outwardly from the casing for the external connection.